The Old Head of Kinsale juts out into the Atlantic from the southern coast of Ireland. For centuries sea captains have used it as a landmark. On 7 May 1915 a local family named Henderson, picnicking on the promontory in bright sunshine, were admiring a huge passenger liner with four raked-back funnels steaming eastward close to shore. Suddenly a vast plume of water and smoke towered above her decks. Within minutes the liner listed to starboard and her bow started to sink. As the stern rose in the water, four great propellers could be clearly discerned. Then she was gone. George Henderson was only six at the time. ‘I can still sit here now,’ he told a TV crew in 1994, ‘and see that great liner just sliding below the waves.’

The Lusitania, launched by Cunard in June 1906 to wrest transatlantic traffic back from the Germans, had completed more than a hundred Atlantic crossings. It left New York for the last time on 1 May, the day the German Embassy printed a warning in the New York Times that travellers sailing on British ships in the war zone around the British Isles did so ‘at their own risk’. Despite the luxurious languor of the voyage, there was a suppressed air of anxiety among the passengers, who included the American tycoon Alfred Vanderbilt and the Welsh mining magnate D.A. Thomas. The German submarine U-20 had already torpedoed three British cargo vessels off the Irish coast. At lunchtime on 7 May its captain, Walther Schwieger, sighted a four-stack passenger liner, clearly British, and dived to intercept her. He fired a single torpedo at 2.10 p.m., and within 18 minutes the ship had disappeared beneath the waves. Of 1962 passengers and crew on board, 1201 lost their lives. Alfred Vanderbilt was among 128 American dead. One Welsh newspaper, apparently in all innocence, proclaimed in banner headlines: ‘great national disaster. d.a. thomas saved.’

For the early 20th century this was the defining act of terrorism against innocent civilians. The principal cause is obvious – the actions of the U-20 – but much has also been written about culpability on the British side, in particular the claim that Churchill, then First Lord of the Admiralty, deliberately sacrificed the Lusitania to draw the United States into the war. Both Diana Preston and David Ramsay deal briskly and effectively with this. Churchill and Jackie Fisher, the First Sea Lord, were preoccupied with the escalating political crisis over Gallipoli. The absence of British naval escorts for the Lusitania in the war zone reflected the generally accepted view that a liner’s best defence against U-boats lay in its own speed. We are talking here, in Preston’s words, of ‘contributory negligence’ at most.

Such conspiracy as there was occurred after the event. The British Government was anxious to conceal the presence of munitions in the Lusitania’s hold. More than four thousand cases of rifle cartridges and 1250 cases of unfused shells had been declared on the cargo manifest and were legal under US law, but Whitehall feared that a widely reported second explosion had been the result of these munitions going off. It therefore tried to shift the blame onto the Lusitania’s captain, William Turner, and also played up talk of a second torpedo. Both Ramsay and Preston are emphatic, however, that the U-20 fired only once, and they broadly agree on what could have caused a single torpedo to sink a 30,000-ton liner in 18 minutes.

In 1903, Cunard had been bailed out by the state when it became obvious that it was losing the transatlantic liner race to the Germans and Americans. The Balfour Government provided a loan of £2.6 million to help build two fast new liners, plus an annual subsidy of £150,000 to keep both in war readiness. The Lusitania and her sister ship, the Mauretania, were designated by the Admiralty as auxiliary war cruisers. Gun mountings were even fitted in 1913 – though not, both authors maintain, any guns. The Titanic, a White Star liner, was fitted with a series of watertight bulkheads running across the ship, and although five were breached when the iceberg bumped along the side, the rest helped the liner to stay afloat and on an even keel for two hours “and forty minutes. The Lusitania, however, was designed to warship specifications. Because the main fear was gunfire from enemy surface ships, her strongest armour plating was above the waterline. The vulnerable “ engine and boiler rooms, surrounded by longitudinal bulkheads linking them to the coal bunkers, which were expected to provide additional protection against shells, were pushed below water level.

Walther Schwieger’s lone torpedo struck near the front of number one boiler-room. It opened up a hole of some two hundred square feet that expanded by the minute. (It’s likely that the gashes along the Titanic’s side amounted in all to twelve square feet.) As water flooded down the open passages to the coal bunkers, number two boiler-room was quickly engulfed, causing a catastrophic loss of power. Moreover, the longitudinal bulkheads ensured that the water was not spread evenly across the ship, as on the Titanic, but confined to the starboard side. Hence the severe list. At this point Captain Turner’s failure to ensure that all the portholes were closed – this was before effective air-conditioning – became a serious contributory factor. The second explosion, described by one witness as ‘a sullen rumble’ from the bowels of the ship, was therefore probably of only secondary importance. Both Preston and Ramsay doubt that the munitions or coaldust were its cause, and suspect a fractured steam pipe. Whatever the explanation, the damage had already been done. One torpedo in the wrong place and the Lusitania was doomed.

Although submarines had been around since the Napoleonic wars – Nelson called them ‘sneak dodges down below’ – they emerged as a serious military weapon only on the eve of World War One. The Lusitania, state-of-the-art technology when first conceived in 1903, was dangerously obsolescent a decade later. What protected her against surface gunfire left her vulnerable to underwater attack.

There is an analogy here with 11 September 2001. Like the Lusitania, the Twin Towers were icons of national commerce and power, and represented the cutting edge of technology. Their load was carried by tightly spaced steel columns girding their perimeter, braced laterally by each floor deck. The destruction by explosion and fire of columns and floors on several storeys therefore transferred excessive loads to the remaining columns. As these loads became unsustainable, one storey collapsed on the next in a ‘pancake’ effect. The towers were designed to cope with the obvious threats, such as earth tremors and strong winds, but, like the Lusitania, were almost defenceless against something novel.

To focus on the technology of vulnerability is, of course, to ignore more than half the story. Why some resort to weapons of terror and what the response should be are more important questions. The Kaiser’s Germany had quite deliberately trampled on the rights of neutrals and non-combatants. Trapped between two great land powers, France and Russia, it developed a strategy to knock the French out of the war before the Russians could attack in the East. Under the Schlieffen Plan, speedy victory in the West required the violation of Belgium’s neutrality, guaranteed by Britain, Prussia and other powers in a treaty signed in 1839. Germany’s Chancellor, Theobald von Bethmann Hollweg, openly admitted that this violation was a breach of international law and promised redress once the war was won. But, he told the Reichstag, ‘we are now in a state of necessity, and necessity knows no law.’

The appeal to necessity has a long history in warfare. In The Rights and Duties of Neutrals Stephen Neff calls it ‘a sort of juridical “wild card” which allows a state to “trump” the normal rights of other states in times of desperation’.* Germany wasn’t the only country to have played it: in 1807 necessity was invoked to justify Nelson’s attack on the neutral Danish fleet at Copenhagen. Faced with encirclement by powerful enemies in World War One, the German Government now cited necessity to justify its practice of unrestricted submarine warfare. With its fleet bottled up in port and Britain applying a tight naval blockade, undersea warfare seemed the only option. Respect for neutral shipping was affirmed by Berlin, but belligerent passenger vessels constituted a grey area because they might be carrying neutral property and persons. In such cases, submarines were supposed to follow long-established rules of cruiser warfare: to come to the surface, order the ship to stop, and then search it for contraband. In 1915 the Germans claimed with justification that this was impossible, since the British were covertly arming their passenger vessels and even hoisting neutral flags as a ruse de guerre. In February 1915 the Lusitania had itself run up the American flag on the last leg of its voyage to Liverpool. With Britannia ruling the waves and waiving the rules, Germany decided to treat any enemy ship as an automatic target, passenger vessels not excluded. Instead of stop and search, the policy was shoot on sight.

That is what Captain Schwieger did on 7 May 1915. He returned home to a hero’s welcome, amid press reports that the Lusitania was an armed auxiliary warship packed with munitions and Canadian troops. But the tone of the response changed as the Kaiser’s Government took stock of the reaction abroad, particularly in the United States. Years later, the journalist Mark Sullivan wrote in 1933, Americans could still remember the moment they read the news. Though not captured on film, the sinking of the Lusitania had the same kind of impact as JFK’s assassination or the attack on the Twin Towers.

Today, of course, the murder of 128 American citizens would provoke swift and massive retaliation. In 1915, however, it elicited only an indignant diplomatic note. President Woodrow Wilson’s immediate, unscripted attempt to cool American tempers – ‘there is such a thing as a man being too proud to fight. There is such a thing as a nation being so right that it does not need to convince others by force that it is right’ – provoked anger in Allied capitals and criticism at home. Yet for all the differences between Wilson’s era and our own, the position that he took over the Lusitania helped shape American foreign policy for the rest of the century.

Wilson was an academic who came late to politics. The son of a Southern Presbyterian minister, he had taught history and politics at Johns Hopkins and Princeton before serving as Princeton’s president from 1902 to 1910. He was almost 54 when he won his first political post as Governor of New Jersey, yet only two years later, in November 1912, he was elected President of the United States. Many writers have taken this chronology to be crucial, arguing that Wilson’s ideas had fully taken shape before he reached the White House. Freud famously discerned an unresolved Oepidus complex, with Wilson cast in the role of Christ and his father as God. Arthur Link, Wilson’s pre-eminent biographer, spoke for a majority of scholars in seeing him as essentially a Christian idealist, gripped by grand but unrealistic ideals, especially the League of Nations, whose rigid commitment to these ideals brought him enormous success but also ultimate failure.

John Thompson offers us a different Wilson. He plays down the President’s Christianity, arguing that this was sincere but not dominating, and portrays him as ‘a practising politician’ who ‘travelled with very little ideological baggage, adopting and abandoning positions as they suited his political interests at the time, and deftly using his exceptional rhetorical ability to cover his tracks’. Not everyone will be convinced – at times Thompson’s pragmatic Wilson sounds more like Harold than Woodrow – but his interpretation presents a stimulating challenge to conventional wisdom and will have to be taken seriously by future writers. The key, he argues, is Wilson’s lifelong fascination as an academic and politician with the nature and potential of leadership in a democracy. He depicts the President’s diplomacy as a pioneering response to the dilemma that would face all modern American leaders: how to craft a policy that both addresses external realities and commands domestic support. An unrealistic policy will not be successful; an unpopular policy cannot be sustained.

The Lusitania crisis provides both a case-study and a precedent. ‘I wish with all my heart that I saw a way to carry out the double wish of our people,’ Wilson wrote privately in June 1915: ‘to maintain a firm front in respect of what we demand of Germany and yet do nothing that might by any possibility involve us in the war.’ His notes demanding reparations for the loss of life and an end to unrestricted U-boat warfare were an attempt to keep that balance. Thus began a war of words with Berlin that lasted nearly a year, punctuated by more American casualties. It was not until May 1916 that the German Government promised to abide by the rules of cruiser warfare. Yet Wilson had elicited that pledge by threatening to break off diplomatic relations. When the Germans reneged in a desperate bid to sever Britain’s transatlantic lifeline in April 1917, the President had little choice but to ask Congress for a declaration of war.

Although that was nearly two years after the Lusitania went down, the position Wilson adopted in 1915 had determined his options. To understand his predicament we have to distinguish neutrality from neutral rights. The former meant staying out of the war, while the latter referred to the rights of neutrals to trade and travel freely in wartime. Traditionally America had asserted both neutrality and neutral rights during Europe’s wars – allowing the New World to ‘fatten on the follies of the Old’ in Jefferson’s felicitous phrase. But in 1914-15 this was no longer possible. That certainly was the view of William Jennings Bryan, the populist Democrat and former Presidential candidate whom Wilson had been obliged to appoint as Secretary of State in 1913. In the new era of undersea warfare, Bryan wanted Wilson to curtail American neutral rights in the interests of American neutrality, notably by warning US citizens that they travelled on belligerent passenger vessels at their own risk.

In retrospect that seems like prudent counsel, so why didn’t Wilson follow Bryan’s advice? Partly because he did not anticipate anything like the Lusitania. The sinking of a British vessel in March, off the west coast of Africa, had resulted in the loss of only one American life. The enormity of 7 May was unimagined. Like the Lusitania, Wilson’s policy was not designed for the realities of U-boat warfare. Both before and after the event, however, he avoided a posture of timid neutrality. He told a Senate critic in February 1916 that he could not ‘consent to any abridgment of the rights of American citizens in any respect. The honour and self-respect of the nation is involved.’ At stake was ‘the very essence of the things that have made America a sovereign nation. She cannot yield them without conceding her own impotency as a nation and making virtual surrender of her independent position among the nations of the world.’ In public he advanced even grander claims for his position: the American flag, he said, ‘stands for the rights of mankind, no matter where they be’.

In principle, both Wilson and Bryan wanted peace with honour. Forced to choose, Bryan believed the first outweighed the second, whereas Wilson’s definition of honour carried too heavy a burden of national and universal rights. Thompson argues that Wilson’s response, which positioned him between Bryan’s pacifism and the bellicosity of Teddy Roosevelt, showed his sensitivity to domestic opinion. Elsewhere, however, he admits that May 1915 was ‘a passing fury’ and that Wilson was prone to exaggerate the assertiveness of American opinion, whose dominant wish was to stay out of the war. As Thompson speculates briefly, the President’s self-confidence may even owe something to his euphoria in May and June 1915 as he courted Edith Bolling Galt, the woman who would become the second Mrs Wilson. After his notorious ‘too proud to fight’ speech, he confessed to her that ‘I do not know just what I said’ because ‘my heart was in such a whirl from that wonderful interview of yesterday.’ Thompson quotes this letter. Preston makes much more of it. Fortunately, it was not available to Freud.

Motivation aside, Wilson adopted a position on neutral rights that was far more assertive than Bryan’s (indeed, Bryan resigned over the President’s response to the Lusitania crisis). Moreover, the extravagant rhetoric about national and universal values was very much Wilson’s own, not forced on him by domestic opinion. Whatever the direct influence on him of Christianity, he espoused a providentialist view of America’s destiny. By 1913 the United States accounted for nearly a third of world manufacturing output. Although self-consciously not a military power, it clearly had the capacity for a greater role on the world stage, and this Wilson believed it could and should assume.

Neutrality was, for Wilson, a means not an end. He wanted peace, but not at any price. When the Germans broke their pledge and resumed unrestricted U-boat warfare in 1917, he struck out for the high moral ground, claiming that German wickedness showed that neutrality was no longer possible for any nation and proclaiming a crusade to ‘make the world safe for democracy’. Here was another slogan that would come back to haunt him, but one which reflected his elevated conception of his country’s mission.

In the isolationist 1930s, Americans reopened the debates of 1915-17. A series of Neutrality Acts were passed by Congress, restricting American rights of trade and travel in time of war. This was Bryan’s revenge, twenty years too late, but it was only a passing phase. After the Fall of France, Roosevelt dismantled or bypassed the Neutrality Acts, edging the nation towards covert co-belligerency with Britain. Once in the war the United States invoked its own doctrines of necessity to justify practices it had condemned a quarter of a century before. A few hours after the surprise attack on Pearl Harbor, Washington ordered commanders in the Pacific to ‘execute unrestricted air and submarine warfare against Japan’. American submariners, although constituting only 2 per cent of US Naval personnel, were responsible for over half the Japanese tonnage sunk during the war – some 1300 warships and merchantmen. In early 1945 the US Army Air Force abandoned the fiction of precision bombing and began massive incendiary raids on Japan’s wooden cities. On 9 March 334 B-29s destroyed 16 square miles of Tokyo in a firestorm that took the lives of 83,000 people – more than the death toll in Hiroshima on 6 August.

While some historic neutrals such as Belgium abandoned neutrality for good after World War Two, others maintained the posture through World War and Cold War – though the wartime records of both Sweden and Switzerland no longer look as simple or pure as their Governments once maintained (see the illuminating recent set of essays edited by Neville Wylie†). In the eyes of Cold War America, however, neutrality was not an acceptable option. In 1956 John Foster Dulles, the US Secretary of State, famously declared that neutrality had become increasingly ‘obsolete’ and that, ‘except under very exceptional circumstances, it is an immoral and shortsighted conception.’ In the global struggle against Communism, it was a case of either with us or against us. That was Wilson’s line in April 1917. And in the wake of the Cold War, the first President Bush proclaimed ‘a new world order’ in language reminiscent of Wilson.

Wilsonianism has indeed been a protean ideology – not easily defined, yet (or perhaps in consequence) deeply influential. In his early career Henry Kissinger was notoriously critical of Wilson’s legacy, arguing that America needed hard-headed realism, not bright-eyed idealism, to guide its foreign policy. In 1994, however, he sounded a different note: ‘Wilson grasped that America’s instinctive isolationism could be overcome only by an appeal to its belief in the exceptional nature of its ideals.’ Thompson takes that as a tribute to a leader ‘who could at once interpret and persuade his fellow-countrymen’. Yet it is also testimony to the perennial dilemma of US policy-makers when trying to mobilise consent in a vast, pluralist, federal society that, even in the age of globalism, is still remarkably self-sufficient and self-absorbed. Proclaiming values is easier than defining interests. Appealing to national uniqueness makes it harder to confront worldly realities. The days of steamships and torpedoes seem a long way from the era of jet aircraft and suicide bombers. But a President who spoke of making the world safe for democracy would have understood both the attractions and the perils of declaring a ‘war on terror’ against a global ‘axis of evil’.